The proposed research concerns the role of non-verbal, attention-directing behaviors (such as looking and pointing) in the acquisition of linguistic deictic terms (words that direct attention, such as personal pronouns). The focus of this research is the language development of autistic children, who have severe difficulty learning to use linguistic deixis. Evidence from studies of normal children has suggested that early experience in using and understanding non-verbal attention-directing behaviors may be an important prerequisite to acquisition of terms such as personal pronouns. We have hypothesized that the failure of autistic children to engage in attention-directing interactions with caretakers may in part underlie their specific in linguistic deixis. By comparing the performance of autistic children with that of language-delayed children, this research will help to show whether these two groups may be differentiated on the basis of their functional use of language or their ability to engage in attention-directing interactions. This research will also compare autistic children who have two-word utterances with autistic children who have litle expressive language. This comparison will allow us to determine whether for autistic children, ability to use language varies directly with ability to engage in attention-directing interactions. Both autistic and language-delayed groups will be compared with a group of normal children in the process of acquiring personal pronouns. Data on use of language and attention-directing gestures will be collected from a free play session and from a structured session through naturalistic elicitation techniques. Videotape techniques and detailed assessment procedures will provide extensive data on the cognitive and social abilities of our participants. Our techniques will allow us to make qualitative evaluations of our groups that may contribute to an improved definition of autistic language and social behavior. We hope to identify developmental differences between the autistic and language-delayed groups that may be of considerable diagnostic significance, and we also expect our analysis to suggest appropriate intervention strategies for use with autistic children.